It is not often that a single experiment opens up a new direction of research. In this report, the optical properties of a series of organic molecules, of the form 2,4-bis((N-methyl-N-alkylamino)phenyl)squarine, which are symmetrical about their centre point, are investigated. By conventional thinking, these molecules should not show any even order non-linear optical effects; the generation of second, fourth or sixth harmonics of the incident light. In fact, significant second harmonics are generated by the materials, x(2)=25-pm v-1. This fact in itself is noteworthy, but the additional fact that the efficiency of the conversion is over two times greater than any other previously reported material is exceptional. The door is now open to an entirely new class of non-linear optical materials. In this report a thorough characterisation of the organic molecules is made by a variety of techniques; polarised second harmonic generation, quartz crystal micro balance and grazing angle X-ray diffraction. A mechanism for this new phenomenon, based on intermolecular charge transfer is developed. In a world of ever tightening pollution control legislation the need for sensors which can accurately measure the concentrations of various pollutant gases is becoming more important. In this report the pollutant sensing properties of a series of organic molecules, 2,4-bis((N-methyl-N-alkylamino)phenyl)squarine, are investigated. The series of compounds was found to be sensitive to nitrogen dioxide in concentrations of as little as 1 part per million in air, but the changes produced in the molecules were non-reversible. It is very rare to accidentally stumble across a molecule with ideal properties. A molecule must usually be modified to achieve optimum properties. In this report the steps taken in the molecular engineering of a new selective and reversible gas sending molecule are also reported. 1-(4-hydroxyphenyl)-2-(1-octadecyl-4-quinolinium iodide) ethene shows sensitivity to ammonia gas in concentrations as low as 25 parts per million in air. The response is fully reversible and can be detected using a surface plasmon resonance based sensor. In the search for new technical solutions to old problems simple solutions are often overlooked. The final section off this report describes a simple gas sensing technique, which had been available in many research institutions, but overlooked in favour of more complex solutions.

The aim of this study was to find out if nejayote produced at household level in Guatemala represents a threat to aquatic ecosystems and, if so, propose sustainable processing, reuse and disposal methods. First, all aspects related to nejayote production were explored. This study presents combined results from literature study on corn consumption and Guatemalan demography, a survey to Guatemalan women of all ethnical groups, nixtamalization replica and solids removal experiments and laboratory analysis. Findings indicate that the source of nejayote are approximate 600 000 tones of corn nixtamalized yearly by Mayan women from the rural areas of Guatemala to prepare tortillas for a population of about 5 000 000. From this activity approximately 300 000 tones of concentrated nejayote are produced and 800 000 tones of water are polluted yearly. Approximate 63% of these volumes are discharged into water ecosystems without treatment due to lack of knowledge of its potential negative impact or reuse properties. The study was done on nejayote produced at national level, but the isolation of the Mayan population within less than 20% of the national territory, suggests higher punctuality of nejayote discharges. Chemical and physical analyses made to samples from the nixtamalization replica confirmed its similarity to industrial nejayote, which has proven to be highly pollutant due to high content of organic matter from corn grain pericarp and germ. Concentrations ranges from 200 to 300 ppm of nitrogen, 160 to 190 ppm of phosphorus and 25 000 to 28 000 ppm of organic matter make it a potential fertilizer or soil conditioner. Studies indicate that it can be safely reused as supplementary food for chickens and pigs, to prepare additional corn based foods for humans or it could be safely discharged into ponds, wetlands or pits to minimize any environmental impact. Although findings point to nejayote as a potential aquatic ecosystem pollutant, this depends on the capacity of the specific recipient aquatic ecosystem to adsorb and process the nutrients and on the volumes and concentration of nutrients of the nejayote discharged that might vary from household to household. However, the nutrient rich nejayote can be seen as a potential resource, instead of a pollutant, to improve the nutritional, social and economical conditions of the Mayan populations. Specially women, an isolated segment of society that lacks opportunities and who, according to findings of this study, start processing corn into tortillas from early childhood and continue throughout all their lifetime without any benefit on return.

Premixed and partially-premixed combustion and ollutant emissions in full-scale gas turbines has been numerically investigated using a massively-parallel Large-Eddy Simulation Combustion Dynamics Model. Through the use of a flamelet library approach, it was observed that CO (Carbon Oxide) and NO (Nitric Oxide) emission can be predicted and match experimental results. The prediction of the CO emission trend is shown to be possible if the influence of the formation of UHC (Unburnt HydroCarbons) via flame extinction is taken into account. Simulations were repeated with two different combustion approach: the G-equation model and the Linear-Eddy Mixing (LEM) Model. Results are similar for these two sets of numerical simulations. The LEM model was used to simulate flame extinction and flame lift-off in a dump combustion chamber. The LEM model is compared to the G-equation model and it was found that the LEM model is more versatile than the G-equation model with regard to accurate simulation of flame propagation in all turbulent premixed combustion regimes. With the addition of heat losses, flame extinction was observed for low equivalence ratio. Numerical simulation of flame propagation with transient inflow conditions were also carried out and demonstrated the ability of the LEM model to accurately simulate flame propagation in the case of a partially-premixed system. In all simulations where flame extinction and flame lift-off was simulated, release of unburnt fuel in the post-flame region through flame extinction was not observed.

The present study is concerned with the feasibility of simulating the release and transport of a ``generic' pollutant within an urban area. The motivation behind this effort lies in the need for accurate and timely predictions of the effects of a pollutant release in a densely populated region, in order to coordinate relief and/or evacuation efforts or design rapid-response scenarios in the event of a possible accident. In order to achieve the above goal, following geometrical, physical, and algorithmic steps have to be taken, generation of a three-dimensional grid, numerical solution of the governing fluid dynamics equations, and numerically solving the transport (reaction/advection/diffusion) equations for a generic pollutant. Some preliminary results will be presented at this time. A sample of representative results will be shown for the generation and transport of a generic pollutant ``plume', using different starting wind conditions and release points. Future efforts in this endeavor will focus on obtaining reasonably accurate simulations of pollutant transport at a reasonable computational price. Specifically, ``reduced' models for the geometry and/or the governing equations will be investigated.

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The overall aim of this thesis was to assess the potential of developing specific quantifiable assays of pollutant damage based on changes on the in vivo optical properties of macroalgae, applicable to laboratory and remote systems. The green macroalgae, E. intestinalis, was exposed to selected trace metals (copper and zinc), triazine herbicides (Irgarol 1051 and atrazine) and a series of alcohols (n =1- 9). The algal in vivo spectral properties, measured using a spectrophotometer fitted with an integrating sphere, determined changes due to exposure, and results were compared with established methods, including growth and fluorescence, to assess algal health status. Each pollutant, except zinc, had a significant (P < 0.05) effect on in vivo spectral properties at the range of concentrations used. The results indicated that the technique has potential to identify the algal systems affected by the pollutant, as signatures obtained appeared to indicate whether change was due to structure or pigments. The technique was sensitive, repeatable, and could detect individual pollutants in a copper/Irgarol 1051 mixture. The results were mathematically interpreted to provide ratios, individual wavelengths, sensitivity figures, web diagrams and QSARs to highlight differences between pollutant effect. The QSAR, obtained from Eintestinalis exposed to a series of alcohols, had a R2 value of 0.9682 using in vivo absorptance at 680 nm and Log Kow, which corresponds with published values of 0.97 using ion leakage with the same species. However, the technique of in vivo spectral properties has the advantage of being non-invasive. Samples of E. intestinalis were collected from different field sites and their in vivo spectral responses could be grouped according to potential pollutants to which they had been exposed. In addition, the potential of extending the technique for use in remote sensing is discussed. It was concluded that the technique of monitoring in vivo spectral properties is an appropriate biomonitor to add to the expanding range of current biomonitors.

Este trabalho buscou estudar os efeitos do nível de Swirl e alteração da massa de combustível injetada nas emissões de poluentes de um motor Diesel. Foram selecionados 15 cabeçotes de uma população de 100 cabeçotes e agrupados pelo nível de Swirl. Como o motor testado utiliza 5 cabeçotes, 15 cabeçotes foram separados e classificados em 3 categorias pelo nível de Swirl. Em seguida, o motor foi montado com as 3 categorias de cabeçotes no dinamômetro com o objetivo de levantar os efeitos nas emissões de gases e parâmetros de desempenho do motor. Foram medidas as emissões de NOx, CO, THC, fuligem, fumaça e consumo de combustível nos 13 pontos do ciclo ESC, complementadas com medições de torque e potência à plena carga. Além disso, nas condições de plena carga foi explorado o efeito da alteração da massa de combustível injetado, pela mudança do ponto final de injeção, nos parâmetros de desempenho e emissões. / This work aimed at the investigation of the effects of the level of Swirl and the amount of fuel mass injected in the emissions of pollutants on a diesel engine. Cylinder heads were selected from a population of 100 cylinder heads and them grouped by Swirl level. As the engine used in the tests have 5 cylinder heads, 15 cylinder heads were separated into 3 categories by the Swirl level. The engine was mounted with the 3 Swirl level cylinder heads categories with the aim to investigate all effects on emissions and performance such as NOx, CO, THC, soot, smoke, fuel consumption, power and torque. The tests were performed following the ESC cycle and exploring the full load curve behavior with changes of the end of injection point, therefore altering the amount of fuel mass injected.

Este trabalho buscou estudar os efeitos do nível de Swirl e alteração da massa de combustível injetada nas emissões de poluentes de um motor Diesel. Foram selecionados 15 cabeçotes de uma população de 100 cabeçotes e agrupados pelo nível de Swirl. Como o motor testado utiliza 5 cabeçotes, 15 cabeçotes foram separados e classificados em 3 categorias pelo nível de Swirl. Em seguida, o motor foi montado com as 3 categorias de cabeçotes no dinamômetro com o objetivo de levantar os efeitos nas emissões de gases e parâmetros de desempenho do motor. Foram medidas as emissões de NOx, CO, THC, fuligem, fumaça e consumo de combustível nos 13 pontos do ciclo ESC, complementadas com medições de torque e potência à plena carga. Além disso, nas condições de plena carga foi explorado o efeito da alteração da massa de combustível injetado, pela mudança do ponto final de injeção, nos parâmetros de desempenho e emissões. / This work aimed at the investigation of the effects of the level of Swirl and the amount of fuel mass injected in the emissions of pollutants on a diesel engine. Cylinder heads were selected from a population of 100 cylinder heads and them grouped by Swirl level. As the engine used in the tests have 5 cylinder heads, 15 cylinder heads were separated into 3 categories by the Swirl level. The engine was mounted with the 3 Swirl level cylinder heads categories with the aim to investigate all effects on emissions and performance such as NOx, CO, THC, soot, smoke, fuel consumption, power and torque. The tests were performed following the ESC cycle and exploring the full load curve behavior with changes of the end of injection point, therefore altering the amount of fuel mass injected.